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linuxdebug/arch/x86/events/intel/pt.c

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null pointer error
2024-07-16 15:50:57 +02:00
// SPDX-License-Identifier: GPL-2.0-only
/*
* Intel(R) Processor Trace PMU driver for perf
* Copyright (c) 2013-2014, Intel Corporation.
*
* Intel PT is specified in the Intel Architecture Instruction Set Extensions
* Programming Reference:
* http://software.intel.com/en-us/intel-isa-extensions
*/
#undef DEBUG
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/types.h>
#include <linux/bits.h>
#include <linux/limits.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <asm/perf_event.h>
#include <asm/insn.h>
#include <asm/io.h>
#include <asm/intel_pt.h>
#include <asm/intel-family.h>
#include "../perf_event.h"
#include "pt.h"
static DEFINE_PER_CPU(struct pt, pt_ctx);
static struct pt_pmu pt_pmu;
/*
* Capabilities of Intel PT hardware, such as number of address bits or
* supported output schemes, are cached and exported to userspace as "caps"
* attribute group of pt pmu device
* (/sys/bus/event_source/devices/intel_pt/caps/) so that userspace can store
* relevant bits together with intel_pt traces.
*
* These are necessary for both trace decoding (payloads_lip, contains address
* width encoded in IP-related packets), and event configuration (bitmasks with
* permitted values for certain bit fields).
*/
#define PT_CAP(_n, _l, _r, _m) \
[PT_CAP_ ## _n] = { .name = __stringify(_n), .leaf = _l, \
.reg = _r, .mask = _m }
static struct pt_cap_desc {
const char *name;
u32 leaf;
u8 reg;
u32 mask;
} pt_caps[] = {
PT_CAP(max_subleaf, 0, CPUID_EAX, 0xffffffff),
PT_CAP(cr3_filtering, 0, CPUID_EBX, BIT(0)),
PT_CAP(psb_cyc, 0, CPUID_EBX, BIT(1)),
PT_CAP(ip_filtering, 0, CPUID_EBX, BIT(2)),
PT_CAP(mtc, 0, CPUID_EBX, BIT(3)),
PT_CAP(ptwrite, 0, CPUID_EBX, BIT(4)),
PT_CAP(power_event_trace, 0, CPUID_EBX, BIT(5)),
PT_CAP(event_trace, 0, CPUID_EBX, BIT(7)),
PT_CAP(tnt_disable, 0, CPUID_EBX, BIT(8)),
PT_CAP(topa_output, 0, CPUID_ECX, BIT(0)),
PT_CAP(topa_multiple_entries, 0, CPUID_ECX, BIT(1)),
PT_CAP(single_range_output, 0, CPUID_ECX, BIT(2)),
PT_CAP(output_subsys, 0, CPUID_ECX, BIT(3)),
PT_CAP(payloads_lip, 0, CPUID_ECX, BIT(31)),
PT_CAP(num_address_ranges, 1, CPUID_EAX, 0x7),
PT_CAP(mtc_periods, 1, CPUID_EAX, 0xffff0000),
PT_CAP(cycle_thresholds, 1, CPUID_EBX, 0xffff),
PT_CAP(psb_periods, 1, CPUID_EBX, 0xffff0000),
};
u32 intel_pt_validate_cap(u32 *caps, enum pt_capabilities capability)
{
struct pt_cap_desc *cd = &pt_caps[capability];
u32 c = caps[cd->leaf * PT_CPUID_REGS_NUM + cd->reg];
unsigned int shift = __ffs(cd->mask);
return (c & cd->mask) >> shift;
}
EXPORT_SYMBOL_GPL(intel_pt_validate_cap);
u32 intel_pt_validate_hw_cap(enum pt_capabilities cap)
{
return intel_pt_validate_cap(pt_pmu.caps, cap);
}
EXPORT_SYMBOL_GPL(intel_pt_validate_hw_cap);
static ssize_t pt_cap_show(struct device *cdev,
struct device_attribute *attr,
char *buf)
{
struct dev_ext_attribute *ea =
container_of(attr, struct dev_ext_attribute, attr);
enum pt_capabilities cap = (long)ea->var;
return snprintf(buf, PAGE_SIZE, "%x\n", intel_pt_validate_hw_cap(cap));
}
static struct attribute_group pt_cap_group __ro_after_init = {
.name = "caps",
};
PMU_FORMAT_ATTR(pt, "config:0" );
PMU_FORMAT_ATTR(cyc, "config:1" );
PMU_FORMAT_ATTR(pwr_evt, "config:4" );
PMU_FORMAT_ATTR(fup_on_ptw, "config:5" );
PMU_FORMAT_ATTR(mtc, "config:9" );
PMU_FORMAT_ATTR(tsc, "config:10" );
PMU_FORMAT_ATTR(noretcomp, "config:11" );
PMU_FORMAT_ATTR(ptw, "config:12" );
PMU_FORMAT_ATTR(branch, "config:13" );
PMU_FORMAT_ATTR(event, "config:31" );
PMU_FORMAT_ATTR(notnt, "config:55" );
PMU_FORMAT_ATTR(mtc_period, "config:14-17" );
PMU_FORMAT_ATTR(cyc_thresh, "config:19-22" );
PMU_FORMAT_ATTR(psb_period, "config:24-27" );
static struct attribute *pt_formats_attr[] = {
&format_attr_pt.attr,
&format_attr_cyc.attr,
&format_attr_pwr_evt.attr,
&format_attr_event.attr,
&format_attr_notnt.attr,
&format_attr_fup_on_ptw.attr,
&format_attr_mtc.attr,
&format_attr_tsc.attr,
&format_attr_noretcomp.attr,
&format_attr_ptw.attr,
&format_attr_branch.attr,
&format_attr_mtc_period.attr,
&format_attr_cyc_thresh.attr,
&format_attr_psb_period.attr,
NULL,
};
static struct attribute_group pt_format_group = {
.name = "format",
.attrs = pt_formats_attr,
};
static ssize_t
pt_timing_attr_show(struct device *dev, struct device_attribute *attr,
char *page)
{
struct perf_pmu_events_attr *pmu_attr =
container_of(attr, struct perf_pmu_events_attr, attr);
switch (pmu_attr->id) {
case 0:
return sprintf(page, "%lu\n", pt_pmu.max_nonturbo_ratio);
case 1:
return sprintf(page, "%u:%u\n",
pt_pmu.tsc_art_num,
pt_pmu.tsc_art_den);
default:
break;
}
return -EINVAL;
}
PMU_EVENT_ATTR(max_nonturbo_ratio, timing_attr_max_nonturbo_ratio, 0,
pt_timing_attr_show);
PMU_EVENT_ATTR(tsc_art_ratio, timing_attr_tsc_art_ratio, 1,
pt_timing_attr_show);
static struct attribute *pt_timing_attr[] = {
&timing_attr_max_nonturbo_ratio.attr.attr,
&timing_attr_tsc_art_ratio.attr.attr,
NULL,
};
static struct attribute_group pt_timing_group = {
.attrs = pt_timing_attr,
};
static const struct attribute_group *pt_attr_groups[] = {
&pt_cap_group,
&pt_format_group,
&pt_timing_group,
NULL,
};
static int __init pt_pmu_hw_init(void)
{
struct dev_ext_attribute *de_attrs;
struct attribute **attrs;
size_t size;
u64 reg;
int ret;
long i;
rdmsrl(MSR_PLATFORM_INFO, reg);
pt_pmu.max_nonturbo_ratio = (reg & 0xff00) >> 8;
/*
* if available, read in TSC to core crystal clock ratio,
* otherwise, zero for numerator stands for "not enumerated"
* as per SDM
*/
if (boot_cpu_data.cpuid_level >= CPUID_TSC_LEAF) {
u32 eax, ebx, ecx, edx;
cpuid(CPUID_TSC_LEAF, &eax, &ebx, &ecx, &edx);
pt_pmu.tsc_art_num = ebx;
pt_pmu.tsc_art_den = eax;
}
/* model-specific quirks */
switch (boot_cpu_data.x86_model) {
case INTEL_FAM6_BROADWELL:
case INTEL_FAM6_BROADWELL_D:
case INTEL_FAM6_BROADWELL_G:
case INTEL_FAM6_BROADWELL_X:
/* not setting BRANCH_EN will #GP, erratum BDM106 */
pt_pmu.branch_en_always_on = true;
break;
default:
break;
}
if (boot_cpu_has(X86_FEATURE_VMX)) {
/*
* Intel SDM, 36.5 "Tracing post-VMXON" says that
* "IA32_VMX_MISC[bit 14]" being 1 means PT can trace
* post-VMXON.
*/
rdmsrl(MSR_IA32_VMX_MISC, reg);
if (reg & BIT(14))
pt_pmu.vmx = true;
}
for (i = 0; i < PT_CPUID_LEAVES; i++) {
cpuid_count(20, i,
&pt_pmu.caps[CPUID_EAX + i*PT_CPUID_REGS_NUM],
&pt_pmu.caps[CPUID_EBX + i*PT_CPUID_REGS_NUM],
&pt_pmu.caps[CPUID_ECX + i*PT_CPUID_REGS_NUM],
&pt_pmu.caps[CPUID_EDX + i*PT_CPUID_REGS_NUM]);
}
ret = -ENOMEM;
size = sizeof(struct attribute *) * (ARRAY_SIZE(pt_caps)+1);
attrs = kzalloc(size, GFP_KERNEL);
if (!attrs)
goto fail;
size = sizeof(struct dev_ext_attribute) * (ARRAY_SIZE(pt_caps)+1);
de_attrs = kzalloc(size, GFP_KERNEL);
if (!de_attrs)
goto fail;
for (i = 0; i < ARRAY_SIZE(pt_caps); i++) {
struct dev_ext_attribute *de_attr = de_attrs + i;
de_attr->attr.attr.name = pt_caps[i].name;
sysfs_attr_init(&de_attr->attr.attr);
de_attr->attr.attr.mode = S_IRUGO;
de_attr->attr.show = pt_cap_show;
de_attr->var = (void *)i;
attrs[i] = &de_attr->attr.attr;
}
pt_cap_group.attrs = attrs;
return 0;
fail:
kfree(attrs);
return ret;
}
#define RTIT_CTL_CYC_PSB (RTIT_CTL_CYCLEACC | \
RTIT_CTL_CYC_THRESH | \
RTIT_CTL_PSB_FREQ)
#define RTIT_CTL_MTC (RTIT_CTL_MTC_EN | \
RTIT_CTL_MTC_RANGE)
#define RTIT_CTL_PTW (RTIT_CTL_PTW_EN | \
RTIT_CTL_FUP_ON_PTW)
/*
* Bit 0 (TraceEn) in the attr.config is meaningless as the
* corresponding bit in the RTIT_CTL can only be controlled
* by the driver; therefore, repurpose it to mean: pass
* through the bit that was previously assumed to be always
* on for PT, thereby allowing the user to *not* set it if
* they so wish. See also pt_event_valid() and pt_config().
*/
#define RTIT_CTL_PASSTHROUGH RTIT_CTL_TRACEEN
#define PT_CONFIG_MASK (RTIT_CTL_TRACEEN | \
RTIT_CTL_TSC_EN | \
RTIT_CTL_DISRETC | \
RTIT_CTL_BRANCH_EN | \
RTIT_CTL_CYC_PSB | \
RTIT_CTL_MTC | \
RTIT_CTL_PWR_EVT_EN | \
RTIT_CTL_EVENT_EN | \
RTIT_CTL_NOTNT | \
RTIT_CTL_FUP_ON_PTW | \
RTIT_CTL_PTW_EN)
static bool pt_event_valid(struct perf_event *event)
{
u64 config = event->attr.config;
u64 allowed, requested;
if ((config & PT_CONFIG_MASK) != config)
return false;
if (config & RTIT_CTL_CYC_PSB) {
if (!intel_pt_validate_hw_cap(PT_CAP_psb_cyc))
return false;
allowed = intel_pt_validate_hw_cap(PT_CAP_psb_periods);
requested = (config & RTIT_CTL_PSB_FREQ) >>
RTIT_CTL_PSB_FREQ_OFFSET;
if (requested && (!(allowed & BIT(requested))))
return false;
allowed = intel_pt_validate_hw_cap(PT_CAP_cycle_thresholds);
requested = (config & RTIT_CTL_CYC_THRESH) >>
RTIT_CTL_CYC_THRESH_OFFSET;
if (requested && (!(allowed & BIT(requested))))
return false;
}
if (config & RTIT_CTL_MTC) {
/*
* In the unlikely case that CPUID lists valid mtc periods,
* but not the mtc capability, drop out here.
*
* Spec says that setting mtc period bits while mtc bit in
* CPUID is 0 will #GP, so better safe than sorry.
*/
if (!intel_pt_validate_hw_cap(PT_CAP_mtc))
return false;
allowed = intel_pt_validate_hw_cap(PT_CAP_mtc_periods);
if (!allowed)
return false;
requested = (config & RTIT_CTL_MTC_RANGE) >>
RTIT_CTL_MTC_RANGE_OFFSET;
if (!(allowed & BIT(requested)))
return false;
}
if (config & RTIT_CTL_PWR_EVT_EN &&
!intel_pt_validate_hw_cap(PT_CAP_power_event_trace))
return false;
if (config & RTIT_CTL_EVENT_EN &&
!intel_pt_validate_hw_cap(PT_CAP_event_trace))
return false;
if (config & RTIT_CTL_NOTNT &&
!intel_pt_validate_hw_cap(PT_CAP_tnt_disable))
return false;
if (config & RTIT_CTL_PTW) {
if (!intel_pt_validate_hw_cap(PT_CAP_ptwrite))
return false;
/* FUPonPTW without PTW doesn't make sense */
if ((config & RTIT_CTL_FUP_ON_PTW) &&
!(config & RTIT_CTL_PTW_EN))
return false;
}
/*
* Setting bit 0 (TraceEn in RTIT_CTL MSR) in the attr.config
* clears the assumption that BranchEn must always be enabled,
* as was the case with the first implementation of PT.
* If this bit is not set, the legacy behavior is preserved
* for compatibility with the older userspace.
*
* Re-using bit 0 for this purpose is fine because it is never
* directly set by the user; previous attempts at setting it in
* the attr.config resulted in -EINVAL.
*/
if (config & RTIT_CTL_PASSTHROUGH) {
/*
* Disallow not setting BRANCH_EN where BRANCH_EN is
* always required.
*/
if (pt_pmu.branch_en_always_on &&
!(config & RTIT_CTL_BRANCH_EN))
return false;
} else {
/*
* Disallow BRANCH_EN without the PASSTHROUGH.
*/
if (config & RTIT_CTL_BRANCH_EN)
return false;
}
return true;
}
/*
* PT configuration helpers
* These all are cpu affine and operate on a local PT
*/
static void pt_config_start(struct perf_event *event)
{
struct pt *pt = this_cpu_ptr(&pt_ctx);
u64 ctl = event->hw.config;
ctl |= RTIT_CTL_TRACEEN;
if (READ_ONCE(pt->vmx_on))
perf_aux_output_flag(&pt->handle, PERF_AUX_FLAG_PARTIAL);
else
wrmsrl(MSR_IA32_RTIT_CTL, ctl);
WRITE_ONCE(event->hw.config, ctl);
}
/* Address ranges and their corresponding msr configuration registers */
static const struct pt_address_range {
unsigned long msr_a;
unsigned long msr_b;
unsigned int reg_off;
} pt_address_ranges[] = {
{
.msr_a = MSR_IA32_RTIT_ADDR0_A,
.msr_b = MSR_IA32_RTIT_ADDR0_B,
.reg_off = RTIT_CTL_ADDR0_OFFSET,
},
{
.msr_a = MSR_IA32_RTIT_ADDR1_A,
.msr_b = MSR_IA32_RTIT_ADDR1_B,
.reg_off = RTIT_CTL_ADDR1_OFFSET,
},
{
.msr_a = MSR_IA32_RTIT_ADDR2_A,
.msr_b = MSR_IA32_RTIT_ADDR2_B,
.reg_off = RTIT_CTL_ADDR2_OFFSET,
},
{
.msr_a = MSR_IA32_RTIT_ADDR3_A,
.msr_b = MSR_IA32_RTIT_ADDR3_B,
.reg_off = RTIT_CTL_ADDR3_OFFSET,
}
};
static u64 pt_config_filters(struct perf_event *event)
{
struct pt_filters *filters = event->hw.addr_filters;
struct pt *pt = this_cpu_ptr(&pt_ctx);
unsigned int range = 0;
u64 rtit_ctl = 0;
if (!filters)
return 0;
perf_event_addr_filters_sync(event);
for (range = 0; range < filters->nr_filters; range++) {
struct pt_filter *filter = &filters->filter[range];
/*
* Note, if the range has zero start/end addresses due
* to its dynamic object not being loaded yet, we just
* go ahead and program zeroed range, which will simply
* produce no data. Note^2: if executable code at 0x0
* is a concern, we can set up an "invalid" configuration
* such as msr_b < msr_a.
*/
/* avoid redundant msr writes */
if (pt->filters.filter[range].msr_a != filter->msr_a) {
wrmsrl(pt_address_ranges[range].msr_a, filter->msr_a);
pt->filters.filter[range].msr_a = filter->msr_a;
}
if (pt->filters.filter[range].msr_b != filter->msr_b) {
wrmsrl(pt_address_ranges[range].msr_b, filter->msr_b);
pt->filters.filter[range].msr_b = filter->msr_b;
}
rtit_ctl |= (u64)filter->config << pt_address_ranges[range].reg_off;
}
return rtit_ctl;
}
static void pt_config(struct perf_event *event)
{
struct pt *pt = this_cpu_ptr(&pt_ctx);
struct pt_buffer *buf = perf_get_aux(&pt->handle);
u64 reg;
/* First round: clear STATUS, in particular the PSB byte counter. */
if (!event->hw.config) {
perf_event_itrace_started(event);
wrmsrl(MSR_IA32_RTIT_STATUS, 0);
}
reg = pt_config_filters(event);
reg |= RTIT_CTL_TRACEEN;
if (!buf->single)
reg |= RTIT_CTL_TOPA;
/*
* Previously, we had BRANCH_EN on by default, but now that PT has
* grown features outside of branch tracing, it is useful to allow
* the user to disable it. Setting bit 0 in the event's attr.config
* allows BRANCH_EN to pass through instead of being always on. See
* also the comment in pt_event_valid().
*/
if (event->attr.config & BIT(0)) {
reg |= event->attr.config & RTIT_CTL_BRANCH_EN;
} else {
reg |= RTIT_CTL_BRANCH_EN;
}
if (!event->attr.exclude_kernel)
reg |= RTIT_CTL_OS;
if (!event->attr.exclude_user)
reg |= RTIT_CTL_USR;
reg |= (event->attr.config & PT_CONFIG_MASK);
event->hw.config = reg;
pt_config_start(event);
}
static void pt_config_stop(struct perf_event *event)
{
struct pt *pt = this_cpu_ptr(&pt_ctx);
u64 ctl = READ_ONCE(event->hw.config);
/* may be already stopped by a PMI */
if (!(ctl & RTIT_CTL_TRACEEN))
return;
ctl &= ~RTIT_CTL_TRACEEN;
if (!READ_ONCE(pt->vmx_on))
wrmsrl(MSR_IA32_RTIT_CTL, ctl);
WRITE_ONCE(event->hw.config, ctl);
/*
* A wrmsr that disables trace generation serializes other PT
* registers and causes all data packets to be written to memory,
* but a fence is required for the data to become globally visible.
*
* The below WMB, separating data store and aux_head store matches
* the consumer's RMB that separates aux_head load and data load.
*/
wmb();
}
/**
* struct topa - ToPA metadata
* @list: linkage to struct pt_buffer's list of tables
* @offset: offset of the first entry in this table in the buffer
* @size: total size of all entries in this table
* @last: index of the last initialized entry in this table
* @z_count: how many times the first entry repeats
*/
struct topa {
struct list_head list;
u64 offset;
size_t size;
int last;
unsigned int z_count;
};
/*
* Keep ToPA table-related metadata on the same page as the actual table,
* taking up a few words from the top
*/
#define TENTS_PER_PAGE \
((PAGE_SIZE - sizeof(struct topa)) / sizeof(struct topa_entry))
/**
* struct topa_page - page-sized ToPA table with metadata at the top
* @table: actual ToPA table entries, as understood by PT hardware
* @topa: metadata
*/
struct topa_page {
struct topa_entry table[TENTS_PER_PAGE];
struct topa topa;
};
static inline struct topa_page *topa_to_page(struct topa *topa)
{
return container_of(topa, struct topa_page, topa);
}
static inline struct topa_page *topa_entry_to_page(struct topa_entry *te)
{
return (struct topa_page *)((unsigned long)te & PAGE_MASK);
}
static inline phys_addr_t topa_pfn(struct topa *topa)
{
return PFN_DOWN(virt_to_phys(topa_to_page(topa)));
}
/* make -1 stand for the last table entry */
#define TOPA_ENTRY(t, i) \
((i) == -1 \
? &topa_to_page(t)->table[(t)->last] \
: &topa_to_page(t)->table[(i)])
#define TOPA_ENTRY_SIZE(t, i) (sizes(TOPA_ENTRY((t), (i))->size))
#define TOPA_ENTRY_PAGES(t, i) (1 << TOPA_ENTRY((t), (i))->size)
static void pt_config_buffer(struct pt_buffer *buf)
{
struct pt *pt = this_cpu_ptr(&pt_ctx);
u64 reg, mask;
void *base;
if (buf->single) {
base = buf->data_pages[0];
mask = (buf->nr_pages * PAGE_SIZE - 1) >> 7;
} else {
base = topa_to_page(buf->cur)->table;
mask = (u64)buf->cur_idx;
}
reg = virt_to_phys(base);
if (pt->output_base != reg) {
pt->output_base = reg;
wrmsrl(MSR_IA32_RTIT_OUTPUT_BASE, reg);
}
reg = 0x7f | (mask << 7) | ((u64)buf->output_off << 32);
if (pt->output_mask != reg) {
pt->output_mask = reg;
wrmsrl(MSR_IA32_RTIT_OUTPUT_MASK, reg);
}
}
/**
* topa_alloc() - allocate page-sized ToPA table
* @cpu: CPU on which to allocate.
* @gfp: Allocation flags.
*
* Return: On success, return the pointer to ToPA table page.
*/
static struct topa *topa_alloc(int cpu, gfp_t gfp)
{
int node = cpu_to_node(cpu);
struct topa_page *tp;
struct page *p;
p = alloc_pages_node(node, gfp | __GFP_ZERO, 0);
if (!p)
return NULL;
tp = page_address(p);
tp->topa.last = 0;
/*
* In case of singe-entry ToPA, always put the self-referencing END
* link as the 2nd entry in the table
*/
if (!intel_pt_validate_hw_cap(PT_CAP_topa_multiple_entries)) {
TOPA_ENTRY(&tp->topa, 1)->base = page_to_phys(p) >> TOPA_SHIFT;
TOPA_ENTRY(&tp->topa, 1)->end = 1;
}
return &tp->topa;
}
/**
* topa_free() - free a page-sized ToPA table
* @topa: Table to deallocate.
*/
static void topa_free(struct topa *topa)
{
free_page((unsigned long)topa);
}
/**
* topa_insert_table() - insert a ToPA table into a buffer
* @buf: PT buffer that's being extended.
* @topa: New topa table to be inserted.
*
* If it's the first table in this buffer, set up buffer's pointers
* accordingly; otherwise, add a END=1 link entry to @topa to the current
* "last" table and adjust the last table pointer to @topa.
*/
static void topa_insert_table(struct pt_buffer *buf, struct topa *topa)
{
struct topa *last = buf->last;
list_add_tail(&topa->list, &buf->tables);
if (!buf->first) {
buf->first = buf->last = buf->cur = topa;
return;
}
topa->offset = last->offset + last->size;
buf->last = topa;
if (!intel_pt_validate_hw_cap(PT_CAP_topa_multiple_entries))
return;
BUG_ON(last->last != TENTS_PER_PAGE - 1);
TOPA_ENTRY(last, -1)->base = topa_pfn(topa);
TOPA_ENTRY(last, -1)->end = 1;
}
/**
* topa_table_full() - check if a ToPA table is filled up
* @topa: ToPA table.
*/
static bool topa_table_full(struct topa *topa)
{
/* single-entry ToPA is a special case */
if (!intel_pt_validate_hw_cap(PT_CAP_topa_multiple_entries))
return !!topa->last;
return topa->last == TENTS_PER_PAGE - 1;
}
/**
* topa_insert_pages() - create a list of ToPA tables
* @buf: PT buffer being initialized.
* @gfp: Allocation flags.
*
* This initializes a list of ToPA tables with entries from
* the data_pages provided by rb_alloc_aux().
*
* Return: 0 on success or error code.
*/
static int topa_insert_pages(struct pt_buffer *buf, int cpu, gfp_t gfp)
{
struct topa *topa = buf->last;
int order = 0;
struct page *p;
p = virt_to_page(buf->data_pages[buf->nr_pages]);
if (PagePrivate(p))
order = page_private(p);
if (topa_table_full(topa)) {
topa = topa_alloc(cpu, gfp);
if (!topa)
return -ENOMEM;
topa_insert_table(buf, topa);
}
if (topa->z_count == topa->last - 1) {
if (order == TOPA_ENTRY(topa, topa->last - 1)->size)
topa->z_count++;
}
TOPA_ENTRY(topa, -1)->base = page_to_phys(p) >> TOPA_SHIFT;
TOPA_ENTRY(topa, -1)->size = order;
if (!buf->snapshot &&
!intel_pt_validate_hw_cap(PT_CAP_topa_multiple_entries)) {
TOPA_ENTRY(topa, -1)->intr = 1;
TOPA_ENTRY(topa, -1)->stop = 1;
}
topa->last++;
topa->size += sizes(order);
buf->nr_pages += 1ul << order;
return 0;
}
/**
* pt_topa_dump() - print ToPA tables and their entries
* @buf: PT buffer.
*/
static void pt_topa_dump(struct pt_buffer *buf)
{
struct topa *topa;
list_for_each_entry(topa, &buf->tables, list) {
struct topa_page *tp = topa_to_page(topa);
int i;
pr_debug("# table @%p, off %llx size %zx\n", tp->table,
topa->offset, topa->size);
for (i = 0; i < TENTS_PER_PAGE; i++) {
pr_debug("# entry @%p (%lx sz %u %c%c%c) raw=%16llx\n",
&tp->table[i],
(unsigned long)tp->table[i].base << TOPA_SHIFT,
sizes(tp->table[i].size),
tp->table[i].end ? 'E' : ' ',
tp->table[i].intr ? 'I' : ' ',
tp->table[i].stop ? 'S' : ' ',
*(u64 *)&tp->table[i]);
if ((intel_pt_validate_hw_cap(PT_CAP_topa_multiple_entries) &&
tp->table[i].stop) ||
tp->table[i].end)
break;
if (!i && topa->z_count)
i += topa->z_count;
}
}
}
/**
* pt_buffer_advance() - advance to the next output region
* @buf: PT buffer.
*
* Advance the current pointers in the buffer to the next ToPA entry.
*/
static void pt_buffer_advance(struct pt_buffer *buf)
{
buf->output_off = 0;
buf->cur_idx++;
if (buf->cur_idx == buf->cur->last) {
if (buf->cur == buf->last)
buf->cur = buf->first;
else
buf->cur = list_entry(buf->cur->list.next, struct topa,
list);
buf->cur_idx = 0;
}
}
/**
* pt_update_head() - calculate current offsets and sizes
* @pt: Per-cpu pt context.
*
* Update buffer's current write pointer position and data size.
*/
static void pt_update_head(struct pt *pt)
{
struct pt_buffer *buf = perf_get_aux(&pt->handle);
u64 topa_idx, base, old;
if (buf->single) {
local_set(&buf->data_size, buf->output_off);
return;
}
/* offset of the first region in this table from the beginning of buf */
base = buf->cur->offset + buf->output_off;
/* offset of the current output region within this table */
for (topa_idx = 0; topa_idx < buf->cur_idx; topa_idx++)
base += TOPA_ENTRY_SIZE(buf->cur, topa_idx);
if (buf->snapshot) {
local_set(&buf->data_size, base);
} else {
old = (local64_xchg(&buf->head, base) &
((buf->nr_pages << PAGE_SHIFT) - 1));
if (base < old)
base += buf->nr_pages << PAGE_SHIFT;
local_add(base - old, &buf->data_size);
}
}
/**
* pt_buffer_region() - obtain current output region's address
* @buf: PT buffer.
*/
static void *pt_buffer_region(struct pt_buffer *buf)
{
return phys_to_virt(TOPA_ENTRY(buf->cur, buf->cur_idx)->base << TOPA_SHIFT);
}
/**
* pt_buffer_region_size() - obtain current output region's size
* @buf: PT buffer.
*/
static size_t pt_buffer_region_size(struct pt_buffer *buf)
{
return TOPA_ENTRY_SIZE(buf->cur, buf->cur_idx);
}
/**
* pt_handle_status() - take care of possible status conditions
* @pt: Per-cpu pt context.
*/
static void pt_handle_status(struct pt *pt)
{
struct pt_buffer *buf = perf_get_aux(&pt->handle);
int advance = 0;
u64 status;
rdmsrl(MSR_IA32_RTIT_STATUS, status);
if (status & RTIT_STATUS_ERROR) {
pr_err_ratelimited("ToPA ERROR encountered, trying to recover\n");
pt_topa_dump(buf);
status &= ~RTIT_STATUS_ERROR;
}
if (status & RTIT_STATUS_STOPPED) {
status &= ~RTIT_STATUS_STOPPED;
/*
* On systems that only do single-entry ToPA, hitting STOP
* means we are already losing data; need to let the decoder
* know.
*/
if (!buf->single &&
(!intel_pt_validate_hw_cap(PT_CAP_topa_multiple_entries) ||
buf->output_off == pt_buffer_region_size(buf))) {
perf_aux_output_flag(&pt->handle,
PERF_AUX_FLAG_TRUNCATED);
advance++;
}
}
/*
* Also on single-entry ToPA implementations, interrupt will come
* before the output reaches its output region's boundary.
*/
if (!intel_pt_validate_hw_cap(PT_CAP_topa_multiple_entries) &&
!buf->snapshot &&
pt_buffer_region_size(buf) - buf->output_off <= TOPA_PMI_MARGIN) {
void *head = pt_buffer_region(buf);
/* everything within this margin needs to be zeroed out */
memset(head + buf->output_off, 0,
pt_buffer_region_size(buf) -
buf->output_off);
advance++;
}
if (advance)
pt_buffer_advance(buf);
wrmsrl(MSR_IA32_RTIT_STATUS, status);
}
/**
* pt_read_offset() - translate registers into buffer pointers
* @buf: PT buffer.
*
* Set buffer's output pointers from MSR values.
*/
static void pt_read_offset(struct pt_buffer *buf)
{
struct pt *pt = this_cpu_ptr(&pt_ctx);
struct topa_page *tp;
if (!buf->single) {
rdmsrl(MSR_IA32_RTIT_OUTPUT_BASE, pt->output_base);
tp = phys_to_virt(pt->output_base);
buf->cur = &tp->topa;
}
rdmsrl(MSR_IA32_RTIT_OUTPUT_MASK, pt->output_mask);
/* offset within current output region */
buf->output_off = pt->output_mask >> 32;
/* index of current output region within this table */
if (!buf->single)
buf->cur_idx = (pt->output_mask & 0xffffff80) >> 7;
}
static struct topa_entry *
pt_topa_entry_for_page(struct pt_buffer *buf, unsigned int pg)
{
struct topa_page *tp;
struct topa *topa;
unsigned int idx, cur_pg = 0, z_pg = 0, start_idx = 0;
/*
* Indicates a bug in the caller.
*/
if (WARN_ON_ONCE(pg >= buf->nr_pages))
return NULL;
/*
* First, find the ToPA table where @pg fits. With high
* order allocations, there shouldn't be many of these.
*/
list_for_each_entry(topa, &buf->tables, list) {
if (topa->offset + topa->size > pg << PAGE_SHIFT)
goto found;
}
/*
* Hitting this means we have a problem in the ToPA
* allocation code.
*/
WARN_ON_ONCE(1);
return NULL;
found:
/*
* Indicates a problem in the ToPA allocation code.
*/
if (WARN_ON_ONCE(topa->last == -1))
return NULL;
tp = topa_to_page(topa);
cur_pg = PFN_DOWN(topa->offset);
if (topa->z_count) {
z_pg = TOPA_ENTRY_PAGES(topa, 0) * (topa->z_count + 1);
start_idx = topa->z_count + 1;
}
/*
* Multiple entries at the beginning of the table have the same size,
* ideally all of them; if @pg falls there, the search is done.
*/
if (pg >= cur_pg && pg < cur_pg + z_pg) {
idx = (pg - cur_pg) / TOPA_ENTRY_PAGES(topa, 0);
return &tp->table[idx];
}
/*
* Otherwise, slow path: iterate through the remaining entries.
*/
for (idx = start_idx, cur_pg += z_pg; idx < topa->last; idx++) {
if (cur_pg + TOPA_ENTRY_PAGES(topa, idx) > pg)
return &tp->table[idx];
cur_pg += TOPA_ENTRY_PAGES(topa, idx);
}
/*
* Means we couldn't find a ToPA entry in the table that does match.
*/
WARN_ON_ONCE(1);
return NULL;
}
static struct topa_entry *
pt_topa_prev_entry(struct pt_buffer *buf, struct topa_entry *te)
{
unsigned long table = (unsigned long)te & ~(PAGE_SIZE - 1);
struct topa_page *tp;
struct topa *topa;
tp = (struct topa_page *)table;
if (tp->table != te)
return --te;
topa = &tp->topa;
if (topa == buf->first)
topa = buf->last;
else
topa = list_prev_entry(topa, list);
tp = topa_to_page(topa);
return &tp->table[topa->last - 1];
}
/**
* pt_buffer_reset_markers() - place interrupt and stop bits in the buffer
* @buf: PT buffer.
* @handle: Current output handle.
*
* Place INT and STOP marks to prevent overwriting old data that the consumer
* hasn't yet collected and waking up the consumer after a certain fraction of
* the buffer has filled up. Only needed and sensible for non-snapshot counters.
*
* This obviously relies on buf::head to figure out buffer markers, so it has
* to be called after pt_buffer_reset_offsets() and before the hardware tracing
* is enabled.
*/
static int pt_buffer_reset_markers(struct pt_buffer *buf,
struct perf_output_handle *handle)
{
unsigned long head = local64_read(&buf->head);
unsigned long idx, npages, wakeup;
if (buf->single)
return 0;
/* can't stop in the middle of an output region */
if (buf->output_off + handle->size + 1 < pt_buffer_region_size(buf)) {
perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
return -EINVAL;
}
/* single entry ToPA is handled by marking all regions STOP=1 INT=1 */
if (!intel_pt_validate_hw_cap(PT_CAP_topa_multiple_entries))
return 0;
/* clear STOP and INT from current entry */
if (buf->stop_te) {
buf->stop_te->stop = 0;
buf->stop_te->intr = 0;
}
if (buf->intr_te)
buf->intr_te->intr = 0;
/* how many pages till the STOP marker */
npages = handle->size >> PAGE_SHIFT;
/* if it's on a page boundary, fill up one more page */
if (!offset_in_page(head + handle->size + 1))
npages++;
idx = (head >> PAGE_SHIFT) + npages;
idx &= buf->nr_pages - 1;
if (idx != buf->stop_pos) {
buf->stop_pos = idx;
buf->stop_te = pt_topa_entry_for_page(buf, idx);
buf->stop_te = pt_topa_prev_entry(buf, buf->stop_te);
}
wakeup = handle->wakeup >> PAGE_SHIFT;
/* in the worst case, wake up the consumer one page before hard stop */
idx = (head >> PAGE_SHIFT) + npages - 1;
if (idx > wakeup)
idx = wakeup;
idx &= buf->nr_pages - 1;
if (idx != buf->intr_pos) {
buf->intr_pos = idx;
buf->intr_te = pt_topa_entry_for_page(buf, idx);
buf->intr_te = pt_topa_prev_entry(buf, buf->intr_te);
}
buf->stop_te->stop = 1;
buf->stop_te->intr = 1;
buf->intr_te->intr = 1;
return 0;
}
/**
* pt_buffer_reset_offsets() - adjust buffer's write pointers from aux_head
* @buf: PT buffer.
* @head: Write pointer (aux_head) from AUX buffer.
*
* Find the ToPA table and entry corresponding to given @head and set buffer's
* "current" pointers accordingly. This is done after we have obtained the
* current aux_head position from a successful call to perf_aux_output_begin()
* to make sure the hardware is writing to the right place.
*
* This function modifies buf::{cur,cur_idx,output_off} that will be programmed
* into PT msrs when the tracing is enabled and buf::head and buf::data_size,
* which are used to determine INT and STOP markers' locations by a subsequent
* call to pt_buffer_reset_markers().
*/
static void pt_buffer_reset_offsets(struct pt_buffer *buf, unsigned long head)
{
struct topa_page *cur_tp;
struct topa_entry *te;
int pg;
if (buf->snapshot)
head &= (buf->nr_pages << PAGE_SHIFT) - 1;
if (!buf->single) {
pg = (head >> PAGE_SHIFT) & (buf->nr_pages - 1);
te = pt_topa_entry_for_page(buf, pg);
cur_tp = topa_entry_to_page(te);
buf->cur = &cur_tp->topa;
buf->cur_idx = te - TOPA_ENTRY(buf->cur, 0);
buf->output_off = head & (pt_buffer_region_size(buf) - 1);
} else {
buf->output_off = head;
}
local64_set(&buf->head, head);
local_set(&buf->data_size, 0);
}
/**
* pt_buffer_fini_topa() - deallocate ToPA structure of a buffer
* @buf: PT buffer.
*/
static void pt_buffer_fini_topa(struct pt_buffer *buf)
{
struct topa *topa, *iter;
if (buf->single)
return;
list_for_each_entry_safe(topa, iter, &buf->tables, list) {
/*
* right now, this is in free_aux() path only, so
* no need to unlink this table from the list
*/
topa_free(topa);
}
}
/**
* pt_buffer_init_topa() - initialize ToPA table for pt buffer
* @buf: PT buffer.
* @size: Total size of all regions within this ToPA.
* @gfp: Allocation flags.
*/
static int pt_buffer_init_topa(struct pt_buffer *buf, int cpu,
unsigned long nr_pages, gfp_t gfp)
{
struct topa *topa;
int err;
topa = topa_alloc(cpu, gfp);
if (!topa)
return -ENOMEM;
topa_insert_table(buf, topa);
while (buf->nr_pages < nr_pages) {
err = topa_insert_pages(buf, cpu, gfp);
if (err) {
pt_buffer_fini_topa(buf);
return -ENOMEM;
}
}
/* link last table to the first one, unless we're double buffering */
if (intel_pt_validate_hw_cap(PT_CAP_topa_multiple_entries)) {
TOPA_ENTRY(buf->last, -1)->base = topa_pfn(buf->first);
TOPA_ENTRY(buf->last, -1)->end = 1;
}
pt_topa_dump(buf);
return 0;
}
static int pt_buffer_try_single(struct pt_buffer *buf, int nr_pages)
{
struct page *p = virt_to_page(buf->data_pages[0]);
int ret = -ENOTSUPP, order = 0;
/*
* We can use single range output mode
* + in snapshot mode, where we don't need interrupts;
* + if the hardware supports it;
* + if the entire buffer is one contiguous allocation.
*/
if (!buf->snapshot)
goto out;
if (!intel_pt_validate_hw_cap(PT_CAP_single_range_output))
goto out;
if (PagePrivate(p))
order = page_private(p);
if (1 << order != nr_pages)
goto out;
/*
* Some processors cannot always support single range for more than
* 4KB - refer errata TGL052, ADL037 and RPL017. Future processors might
* also be affected, so for now rather than trying to keep track of
* which ones, just disable it for all.
*/
if (nr_pages > 1)
goto out;
buf->single = true;
buf->nr_pages = nr_pages;
ret = 0;
out:
return ret;
}
/**
* pt_buffer_setup_aux() - set up topa tables for a PT buffer
* @cpu: Cpu on which to allocate, -1 means current.
* @pages: Array of pointers to buffer pages passed from perf core.
* @nr_pages: Number of pages in the buffer.
* @snapshot: If this is a snapshot/overwrite counter.
*
* This is a pmu::setup_aux callback that sets up ToPA tables and all the
* bookkeeping for an AUX buffer.
*
* Return: Our private PT buffer structure.
*/
static void *
pt_buffer_setup_aux(struct perf_event *event, void **pages,
int nr_pages, bool snapshot)
{
struct pt_buffer *buf;
int node, ret, cpu = event->cpu;
if (!nr_pages)
return NULL;
/*
* Only support AUX sampling in snapshot mode, where we don't
* generate NMIs.
*/
if (event->attr.aux_sample_size && !snapshot)
return NULL;
if (cpu == -1)
cpu = raw_smp_processor_id();
node = cpu_to_node(cpu);
buf = kzalloc_node(sizeof(struct pt_buffer), GFP_KERNEL, node);
if (!buf)
return NULL;
buf->snapshot = snapshot;
buf->data_pages = pages;
buf->stop_pos = -1;
buf->intr_pos = -1;
INIT_LIST_HEAD(&buf->tables);
ret = pt_buffer_try_single(buf, nr_pages);
if (!ret)
return buf;
ret = pt_buffer_init_topa(buf, cpu, nr_pages, GFP_KERNEL);
if (ret) {
kfree(buf);
return NULL;
}
return buf;
}
/**
* pt_buffer_free_aux() - perf AUX deallocation path callback
* @data: PT buffer.
*/
static void pt_buffer_free_aux(void *data)
{
struct pt_buffer *buf = data;
pt_buffer_fini_topa(buf);
kfree(buf);
}
static int pt_addr_filters_init(struct perf_event *event)
{
struct pt_filters *filters;
int node = event->cpu == -1 ? -1 : cpu_to_node(event->cpu);
if (!intel_pt_validate_hw_cap(PT_CAP_num_address_ranges))
return 0;
filters = kzalloc_node(sizeof(struct pt_filters), GFP_KERNEL, node);
if (!filters)
return -ENOMEM;
if (event->parent)
memcpy(filters, event->parent->hw.addr_filters,
sizeof(*filters));
event->hw.addr_filters = filters;
return 0;
}
static void pt_addr_filters_fini(struct perf_event *event)
{
kfree(event->hw.addr_filters);
event->hw.addr_filters = NULL;
}
#ifdef CONFIG_X86_64
/* Clamp to a canonical address greater-than-or-equal-to the address given */
static u64 clamp_to_ge_canonical_addr(u64 vaddr, u8 vaddr_bits)
{
return __is_canonical_address(vaddr, vaddr_bits) ?
vaddr :
-BIT_ULL(vaddr_bits - 1);
}
/* Clamp to a canonical address less-than-or-equal-to the address given */
static u64 clamp_to_le_canonical_addr(u64 vaddr, u8 vaddr_bits)
{
return __is_canonical_address(vaddr, vaddr_bits) ?
vaddr :
BIT_ULL(vaddr_bits - 1) - 1;
}
#else
#define clamp_to_ge_canonical_addr(x, y) (x)
#define clamp_to_le_canonical_addr(x, y) (x)
#endif
static int pt_event_addr_filters_validate(struct list_head *filters)
{
struct perf_addr_filter *filter;
int range = 0;
list_for_each_entry(filter, filters, entry) {
/*
* PT doesn't support single address triggers and
* 'start' filters.
*/
if (!filter->size ||
filter->action == PERF_ADDR_FILTER_ACTION_START)
return -EOPNOTSUPP;
if (++range > intel_pt_validate_hw_cap(PT_CAP_num_address_ranges))
return -EOPNOTSUPP;
}
return 0;
}
static void pt_event_addr_filters_sync(struct perf_event *event)
{
struct perf_addr_filters_head *head = perf_event_addr_filters(event);
unsigned long msr_a, msr_b;
struct perf_addr_filter_range *fr = event->addr_filter_ranges;
struct pt_filters *filters = event->hw.addr_filters;
struct perf_addr_filter *filter;
int range = 0;
if (!filters)
return;
list_for_each_entry(filter, &head->list, entry) {
if (filter->path.dentry && !fr[range].start) {
msr_a = msr_b = 0;
} else {
unsigned long n = fr[range].size - 1;
unsigned long a = fr[range].start;
unsigned long b;
if (a > ULONG_MAX - n)
b = ULONG_MAX;
else
b = a + n;
/*
* Apply the offset. 64-bit addresses written to the
* MSRs must be canonical, but the range can encompass
* non-canonical addresses. Since software cannot
* execute at non-canonical addresses, adjusting to
* canonical addresses does not affect the result of the
* address filter.
*/
msr_a = clamp_to_ge_canonical_addr(a, boot_cpu_data.x86_virt_bits);
msr_b = clamp_to_le_canonical_addr(b, boot_cpu_data.x86_virt_bits);
if (msr_b < msr_a)
msr_a = msr_b = 0;
}
filters->filter[range].msr_a = msr_a;
filters->filter[range].msr_b = msr_b;
if (filter->action == PERF_ADDR_FILTER_ACTION_FILTER)
filters->filter[range].config = 1;
else
filters->filter[range].config = 2;
range++;
}
filters->nr_filters = range;
}
/**
* intel_pt_interrupt() - PT PMI handler
*/
void intel_pt_interrupt(void)
{
struct pt *pt = this_cpu_ptr(&pt_ctx);
struct pt_buffer *buf;
struct perf_event *event = pt->handle.event;
/*
* There may be a dangling PT bit in the interrupt status register
* after PT has been disabled by pt_event_stop(). Make sure we don't
* do anything (particularly, re-enable) for this event here.
*/
if (!READ_ONCE(pt->handle_nmi))
return;
if (!event)
return;
pt_config_stop(event);
buf = perf_get_aux(&pt->handle);
if (!buf)
return;
pt_read_offset(buf);
pt_handle_status(pt);
pt_update_head(pt);
perf_aux_output_end(&pt->handle, local_xchg(&buf->data_size, 0));
if (!event->hw.state) {
int ret;
buf = perf_aux_output_begin(&pt->handle, event);
if (!buf) {
event->hw.state = PERF_HES_STOPPED;
return;
}
pt_buffer_reset_offsets(buf, pt->handle.head);
/* snapshot counters don't use PMI, so it's safe */
ret = pt_buffer_reset_markers(buf, &pt->handle);
if (ret) {
perf_aux_output_end(&pt->handle, 0);
return;
}
pt_config_buffer(buf);
pt_config_start(event);
}
}
void intel_pt_handle_vmx(int on)
{
struct pt *pt = this_cpu_ptr(&pt_ctx);
struct perf_event *event;
unsigned long flags;
/* PT plays nice with VMX, do nothing */
if (pt_pmu.vmx)
return;
/*
* VMXON will clear RTIT_CTL.TraceEn; we need to make
* sure to not try to set it while VMX is on. Disable
* interrupts to avoid racing with pmu callbacks;
* concurrent PMI should be handled fine.
*/
local_irq_save(flags);
WRITE_ONCE(pt->vmx_on, on);
/*
* If an AUX transaction is in progress, it will contain
* gap(s), so flag it PARTIAL to inform the user.
*/
event = pt->handle.event;
if (event)
perf_aux_output_flag(&pt->handle,
PERF_AUX_FLAG_PARTIAL);
/* Turn PTs back on */
if (!on && event)
wrmsrl(MSR_IA32_RTIT_CTL, event->hw.config);
local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(intel_pt_handle_vmx);
/*
* PMU callbacks
*/
static void pt_event_start(struct perf_event *event, int mode)
{
struct hw_perf_event *hwc = &event->hw;
struct pt *pt = this_cpu_ptr(&pt_ctx);
struct pt_buffer *buf;
buf = perf_aux_output_begin(&pt->handle, event);
if (!buf)
goto fail_stop;
pt_buffer_reset_offsets(buf, pt->handle.head);
if (!buf->snapshot) {
if (pt_buffer_reset_markers(buf, &pt->handle))
goto fail_end_stop;
}
WRITE_ONCE(pt->handle_nmi, 1);
hwc->state = 0;
pt_config_buffer(buf);
pt_config(event);
return;
fail_end_stop:
perf_aux_output_end(&pt->handle, 0);
fail_stop:
hwc->state = PERF_HES_STOPPED;
}
static void pt_event_stop(struct perf_event *event, int mode)
{
struct pt *pt = this_cpu_ptr(&pt_ctx);
/*
* Protect against the PMI racing with disabling wrmsr,
* see comment in intel_pt_interrupt().
*/
WRITE_ONCE(pt->handle_nmi, 0);
pt_config_stop(event);
if (event->hw.state == PERF_HES_STOPPED)
return;
event->hw.state = PERF_HES_STOPPED;
if (mode & PERF_EF_UPDATE) {
struct pt_buffer *buf = perf_get_aux(&pt->handle);
if (!buf)
return;
if (WARN_ON_ONCE(pt->handle.event != event))
return;
pt_read_offset(buf);
pt_handle_status(pt);
pt_update_head(pt);
if (buf->snapshot)
pt->handle.head =
local_xchg(&buf->data_size,
buf->nr_pages << PAGE_SHIFT);
perf_aux_output_end(&pt->handle, local_xchg(&buf->data_size, 0));
}
}
static long pt_event_snapshot_aux(struct perf_event *event,
struct perf_output_handle *handle,
unsigned long size)
{
struct pt *pt = this_cpu_ptr(&pt_ctx);
struct pt_buffer *buf = perf_get_aux(&pt->handle);
unsigned long from = 0, to;
long ret;
if (WARN_ON_ONCE(!buf))
return 0;
/*
* Sampling is only allowed on snapshot events;
* see pt_buffer_setup_aux().
*/
if (WARN_ON_ONCE(!buf->snapshot))
return 0;
/*
* Here, handle_nmi tells us if the tracing is on
*/
if (READ_ONCE(pt->handle_nmi))
pt_config_stop(event);
pt_read_offset(buf);
pt_update_head(pt);
to = local_read(&buf->data_size);
if (to < size)
from = buf->nr_pages << PAGE_SHIFT;
from += to - size;
ret = perf_output_copy_aux(&pt->handle, handle, from, to);
/*
* If the tracing was on when we turned up, restart it.
* Compiler barrier not needed as we couldn't have been
* preempted by anything that touches pt->handle_nmi.
*/
if (pt->handle_nmi)
pt_config_start(event);
return ret;
}
static void pt_event_del(struct perf_event *event, int mode)
{
pt_event_stop(event, PERF_EF_UPDATE);
}
static int pt_event_add(struct perf_event *event, int mode)
{
struct pt *pt = this_cpu_ptr(&pt_ctx);
struct hw_perf_event *hwc = &event->hw;
int ret = -EBUSY;
if (pt->handle.event)
goto fail;
if (mode & PERF_EF_START) {
pt_event_start(event, 0);
ret = -EINVAL;
if (hwc->state == PERF_HES_STOPPED)
goto fail;
} else {
hwc->state = PERF_HES_STOPPED;
}
ret = 0;
fail:
return ret;
}
static void pt_event_read(struct perf_event *event)
{
}
static void pt_event_destroy(struct perf_event *event)
{
pt_addr_filters_fini(event);
x86_del_exclusive(x86_lbr_exclusive_pt);
}
static int pt_event_init(struct perf_event *event)
{
if (event->attr.type != pt_pmu.pmu.type)
return -ENOENT;
if (!pt_event_valid(event))
return -EINVAL;
if (x86_add_exclusive(x86_lbr_exclusive_pt))
return -EBUSY;
if (pt_addr_filters_init(event)) {
x86_del_exclusive(x86_lbr_exclusive_pt);
return -ENOMEM;
}
event->destroy = pt_event_destroy;
return 0;
}
void cpu_emergency_stop_pt(void)
{
struct pt *pt = this_cpu_ptr(&pt_ctx);
if (pt->handle.event)
pt_event_stop(pt->handle.event, PERF_EF_UPDATE);
}
int is_intel_pt_event(struct perf_event *event)
{
return event->pmu == &pt_pmu.pmu;
}
static __init int pt_init(void)
{
int ret, cpu, prior_warn = 0;
BUILD_BUG_ON(sizeof(struct topa) > PAGE_SIZE);
if (!boot_cpu_has(X86_FEATURE_INTEL_PT))
return -ENODEV;
cpus_read_lock();
for_each_online_cpu(cpu) {
u64 ctl;
ret = rdmsrl_safe_on_cpu(cpu, MSR_IA32_RTIT_CTL, &ctl);
if (!ret && (ctl & RTIT_CTL_TRACEEN))
prior_warn++;
}
cpus_read_unlock();
if (prior_warn) {
x86_add_exclusive(x86_lbr_exclusive_pt);
pr_warn("PT is enabled at boot time, doing nothing\n");
return -EBUSY;
}
ret = pt_pmu_hw_init();
if (ret)
return ret;
if (!intel_pt_validate_hw_cap(PT_CAP_topa_output)) {
pr_warn("ToPA output is not supported on this CPU\n");
return -ENODEV;
}
if (!intel_pt_validate_hw_cap(PT_CAP_topa_multiple_entries))
pt_pmu.pmu.capabilities = PERF_PMU_CAP_AUX_NO_SG;
pt_pmu.pmu.capabilities |= PERF_PMU_CAP_EXCLUSIVE | PERF_PMU_CAP_ITRACE;
pt_pmu.pmu.attr_groups = pt_attr_groups;
pt_pmu.pmu.task_ctx_nr = perf_sw_context;
pt_pmu.pmu.event_init = pt_event_init;
pt_pmu.pmu.add = pt_event_add;
pt_pmu.pmu.del = pt_event_del;
pt_pmu.pmu.start = pt_event_start;
pt_pmu.pmu.stop = pt_event_stop;
pt_pmu.pmu.snapshot_aux = pt_event_snapshot_aux;
pt_pmu.pmu.read = pt_event_read;
pt_pmu.pmu.setup_aux = pt_buffer_setup_aux;
pt_pmu.pmu.free_aux = pt_buffer_free_aux;
pt_pmu.pmu.addr_filters_sync = pt_event_addr_filters_sync;
pt_pmu.pmu.addr_filters_validate = pt_event_addr_filters_validate;
pt_pmu.pmu.nr_addr_filters =
intel_pt_validate_hw_cap(PT_CAP_num_address_ranges);
ret = perf_pmu_register(&pt_pmu.pmu, "intel_pt", -1);
return ret;
}
arch_initcall(pt_init);